What is the fastest way of getting the fraction part of a floating point number?

[ME]

What is the fastest way of getting the fraction part of a floating point
number?

So, if I have a float 10.3 I want to get a float with value 0.3 fast.

Thanks

 

[int2str]

What is the fastest way of getting the fraction part of a floating point
number?

This is a fairly trivial problem. I'd hate to do your homework for you.
Have you already tried any aproaches and found them too slow?

So, if I have a float 10.3 I want to get a float with value 0.3 fast.

Define "fast" in this context?
Lines of code/coding time fast or runtime fast?

Cheers,
Andre